The present invention relates to a tool for machining operations such as grinding, polishing, milling, cutting-off or honing workpieces, particularly for machining workpieces made of metal, where the tool features at least one machining die and where at least the working area of said die consists of a composite material that contains a hard material.
A tool for machining of the aforementioned type is known from the German Patent No. DE-A1 41 06 005. Such tools are used in various applications that basically include the areas of milling, cutting, honing and grinding by means of material removal. Very important in such processes is a precise removal of the material. In addition, such tools should achieve a long service life, that is, it should be possible to use them over a long period with appropriate reproducible and controllable material removal in regard to the desired precision as well. The service life of such tools is basically determined by the hard materials that are present in the working area of the tool. Such hard materials exhibit sharp-edges structures due to the fact that they are crystalline components. Over the duration of machining, this sharp-edged crystalline structure is destroyed such that the abrasive effect of the tool is reduced. Depending on the type of materials being machined with such a tool and, additionally, depending on the machining speed, that is, the speed that the tool exerts on the surface to be machined, and the high temperatures that the tool must withstand, will occur especially in the working area.
The grinding and cutting tool as described in the above referenced German Patent No. DE-A1 41 06 005, includes a substrate body with a synthetic material matrix where the substrate body is carbon fiber enforced. A coating that contains hard materials in the form of diamond or boron nitride abrasive grains in the binding agent is applied to the substrate body itself. An electroplated or electroless deposited metal coating is situated on the substrate body as interim coating between the substrate body and the coating to obtain a better bond of the abrasive coating on the substrate body. The problem with such abrasion tools is that the temperature resistance is limited by that of the synthetic material. The synthetic material tends to become soft or to lose its bonding capacity, especially at high temperature influences, such that, especially at such conditions the inherent stability of the tool can no longer be ensured for precision work. This also results in complicated tool structures, for example, those to manufacture toothings, not being able to be manufactured such that they keep their stability, and thus, their shape, over an extended service life.
The U.S. Pat. No. 4,504,284 discloses a tool with a cubic carrier, where at least one of its edges is built as a cutting edge. The core body or carrier includes a filler material, carbon fibers and carbon black. The at least one cutting edge is located at one edge of the body and consists of diamond or cubic boron nitride crystals and is connected to said carrier body by an interim layer consisting of .alpha.- or .beta.-silicon carbide, or mixtures thereof.
The Japanese Patent No. JP-A-06091541 discloses a grinding wheel whose deformation size is to be reduced when it is rotated under high speed (in relation to the centrifugal forces affecting the grinding wheel). For this purpose, the grinding wheel is made by hardening laminated material through epoxy resins and such, after carbon fibers are wound and laminated in the direction of the circumference. Such coiling strengthens the direction of the circumference of the grinding wheel. Due to the use of epoxy resins as a binding agent to harden the carbon structure, this grinding wheel is not designed for, or cannot be used at high temperatures, because an organic binding agent, such as epoxy resin, softens already at relatively low temperatures and thus loses the strength aimed for.
Finally, the U.S. Pat. No. 4,353,953 relates to an integral composite of polycrystalline diamond and/or cubic boron nitride fibers integrally bonded to a substrate supporting phase. The crystals in the phase of the polycrystalline diamond and/or cubic boron nitride are bonded to the phase of the carrier structure by a medium containing silicon carbide and elemental silicon. Thus, the material is present as a two-layer system, namely the crystals, such as diamonds that are bonded to a carrier body using Si and SiC.